I asked him, “If paradigms are really incommensurable, how is history of science possible? Wouldn’t we be merely interpreting the past in the light of the present? Wouldn’t the past be inaccessible to us? Wouldn’t it be ‘incommensurable?’ ” 
He started moaning. He put his head in his hands and was muttering, “He’s trying to kill me. He’s trying to kill me.”
And then I added, “…except for someone who imagines himself to be God.”
It was at this point that Kuhn threw the ashtray at me.